For me it shouldn't be encouraged, giving gifts for outstanding academic performance should be done personally that is; when a parent sees a child improving and then give gifts it's wise, than promising or consistently giving.

The whole of education is for your child to be better at navigating the world than you did, which bring success and peace of mind, the moment this isn't passed down to the child it's a waste of time because it will build children with the mindset of gifts being a reward of anything you do, which will amount to them becoming attention seekers in the long run.